This is a real mystery I thought I'd share. My girls have recently molted so I knew the egg production would be down. They have all finished molting and have been in the nest boxes but I haven't been getting many eggs. (4-8 eggs a day from 15 girls). I have 6 nest boxes in this coop. I was getting 12-14 eggs a day. Awhile back I had found a couple of broken eggs outside of my coop where the chickens can't get to. I put a camera in the coop and the only thing I saw was a rat. I put out rat baits and killed and disposed of 3 rats. I disconnected the camera as I had another camera hooked up because I had someone steeling my eggs I sell and money out of my money jar. I caught him on camera and told him if he came back on my property I would turn the video over to the police. He hasn't been back. Earlier today when I checked on my girls all the nest boxes had one of the girls in each of them. When I went out to collect the eggs later there was only one egg in one of the nest boxes and a broken egg outside of the coop where the chickens can't get to, so I reconnected up the camera in the coop. I am recording on a DVR. My guesses are a rat, snake or a two legged egg thief.
